1. Technical Field
The present disclosure relates to biosourced polycarbonate, and specifically to biosourced polycarbonate compositions having improved flame retardancy.
2. Technical Background
Polymers based on aliphatic diols derived from biologically-based sources are of great interest in the plastics industry and in manufacturing, for the preparation of materials and products that can be derived from inexpensive, renewable sources and that also are biodegradable, and thereby have a low net environmental impact. Of particular interest are polymers based on isosorbides. These materials are of great interest to the chemical industry, and in particular in the production of polymeric materials such as polycarbonates, because such aliphatic diols can be produced from renewable resources rather than from the petroleum feedstocks used to prepare other monomers useful in the production of polycarbonates, such as bisphenol monomers. This bio-sourced polycarbonate (PC) can have high tensile modulus, scratch resistance, and can be processed at 250° C.
For practical applications, polycarbonate incorporating isosorbide needs a balance of properties to be useful. Polycarbonates should have sufficiently high molecular weight for desirable mechanical properties, and sufficiently low glass transition temperatures and flow to be useful in molding and extrusion applications. In addition, because of their broad use, particularly in electronic applications, it is desirable to provide polycarbonates with flame retardancy. While bio-sourced polycarbonate can provide improved mechanical properties over conventional petroleum based polycarbonate materials, existing bio-sourced polycarbonate materials exhibit poor flame resistance and impact strength.
Nonhalogenated flame retardants have been proposed for polycarbonates, including various fillers, phosphorus-containing compounds, and certain salts. It has been difficult to meet the strictest standards of flame retardancy using the foregoing flame retardants, however, without also using brominated and/or chlorinated flame retardants, particularly in thin samples. In addition, existing non-brominated and/or non-chlorinated flame retardants can adversely affect desirable physical properties of the polycarbonate compositions, particularly impact strength.
Thus, there remains a continuing desire in the industry for continued improvement in flame retardance, including a need for polycarbonate compositions having improved flame retardance without use of brominated and/or chlorinated flame retardants. It would also be advantageous if improved flame retardance could be achieved without substantial degradation of properties such as impact strength. These needs and other needs are satisfied by the compositions and methods of the present disclosure.